Goldman Sachs and JPMorgan are squaring up against hedge funds in the fight over a Brexit

Fight night in Europe.Chris McGrath/Getty Images for IFLGoldman Sachs and JPMorgan are pouring cash into the campaign group fighting to keep Britain in Europe, ahead of a referendum on the issue that could come as soon as this summer.

Sky News reported on Wednesday that Goldman Sachs is donating "hundreds of thousands of pounds" to campaign group Britain Stronger in Europe, led by Stuart Rose, the former CEO of Marks & Spencer.

The division in finance is not so cut and dry, however. David Harding, the founder of hedge fund Winton Capital Management, is on the board of pro-EU campaign group Stronger in Europe and has reportedly donated several million. Egerton Capital's John Armitage is also donating to the Stronger in Europe campaign.

The business world is getting increasingly edgy about Britain's looming referendum on whether to remain in the European Union. Many international businesses with a presence here, such as Goldman and JPMorgan, worry it could place a burden on their UK operations.